Silicon substrates used for semiconductor manufacturing often have a silicon oxide that forms on surfaces during processing, greatly increasing the resistivity of any contacts formed on the substrate. A reactive silicide can be used to interact with the silicon oxide to form a better contact region. Aluminum, often used as a contact, adversely reacts with the silicide and underlying silicon, causing junction failures. However, titanium silicide was found to produce a superior contact region while enabling a titanium nitride barrier layer to be used, reducing the silicon adsorption issues with aluminum.
For these reasons, titanium silicide is often used to form ohmic contacts and to reduce contact resistance of local transistor connections. During the formation of a titanium silicide layer on a substrate, silicon is often consumed from the substrate causing a reduction in silicon material and a low silicon to silicon oxide selectivity ratio in the substrate. Generally, high temperatures (e.g. 700 degrees Celsius) are often used during the titanium silicide deposition process.
Accordingly, the inventors have developed an improved process for depositing titanium silicide and other types of films on substrates.